Pat Boone's 1997 album, In A Metal Mood: No More Mr. Nice Guy was completely composed of covers of heavy metal songs, as opposed to his usual fare of R&B, country, and gospel (though they were still done in his milquetoast Big Band/Lounge-style, of course). The CD cover featured the normally clean-cut Boone in leather and chains, an outfit he would also wear at the 1997 American Music Awards. He looked ridiculous, but it didn't do him any favors with the Moral Guardians that make up his primary demographic, who thought he was being serious.
This review proves that, amazingly, even some critics didn't get that it was a joke.
The Colors Album by Between The Buried and Me (Can't say anything about the other albums) has this in each song. For example, Ants of The Sky has polka, Pink Floyd-esque guitar solo, thrashing a-la Metaliica and Megadeth, and intense speed-metal screaming, melodic sections that would make Joe Satriani and Dream Theater proud, and thudding doom-metal sections. In a single song. The thing is that the styles switch nearly immediately, and doesn't sound bad.
Neil Young put out three such albums in a row, much to the consternation of his label (Geffen famously tried to sue him for delivering "unrepresentative material"): First there was the heavily synth-filled Trans, then The Fifties rockabilly throwback of Everybody's Rockin', and finally the country album Old Ways.
The first eleven songs on the RemedyDrive album Magnify are all pretty standard rock (and the occasional bass solo). The last one, "Smile Upon Me", is acapella three-part harmony.
By 1993, R.E.M. had 2 massively successful albums with Out of Time (Shiny Happy People, Losing My Religion), and Automatic for the People (Everybody Hurts, Man on the Moon). Both albums, especially the latter, were relatively slow, emotional albums, with string and acoustic instruments everywhere. In 1994, however, they released Monster, with loud, grunge-y, distorted guitar on every single track.
Incidentally, those two prior albums fit the trope as well, as the band's major label contract was triggered by the success of the 1987 album Document (It's the End of the World As We Know It, The One I Love), which consisted almost entirely of songs that were, by the band's standards, real rockers. The interceding album, 1989's Green, seemed to be following that pattern, with just a few acoustic songs between upbeat rock songs like "Stand," "Orange Crush," and "Pop Song '89."
Keane's first 2 albums were straight piano rock, very similar to Coldplay or Ben Folds. Beginning with their 3rd album, they focused almost entirely on synths, electronic drum beats, heavy bass lines, and guitars.
"Golden Brown", a sincere, harpsichord-led baroque pop single by punk band The Stranglers. It is their most acclaimed, popular and best selling song.
This goes for their entire career from that moment on, as they shifted to moody baroque pop, and later to AOR.
"Revolution 9" by The Beatles isn't like anything else out there.
Minor example: A Day in the Life is a soft, sad-esque song about a guy who reads in the newspaper the story of an unlucky man, the war, a car crash, a suicide, etc. By the middle of the song, it starts an upbeat ballad about going late for work.
Hardcore Punk band The Bronx, after releasing three self-titled albums, released an album of mariachi music under the name "Mariachi El Bronx" in 2009, followed by another in 2011. Both albums are critically acclaimed.
Outkast did this twice in a row. 2003's Speakerboxxx/The Love Below was a double album with each disc being a solo effort from one half of the duo: Big Boi's Speakerboxxx a conventional hip-hop album and Andre3000's The Love Below being more experimental. In 2006 they released Idlewild, the soundtrack to their 20's-era musical, meaning most songs were more of a jazz style, plus there were only a couple songs that Big Boi and Andre performed together. To recap, Outkast has not released a standard album since 2000's Stankonia.
While Tori Amos' sound evolves with every album, 1999's Strange Little Girls is a Cover Album of songs originally performed by men, exploring what it means to be a man from a woman's perspective.
Bob Dylan's been known to do this from time to time and has had many different genres but Empire Burlesque stands out being a uncharacteristic (though not for The Eighties) heavily produced synth pop affair (with one song even leaning slightly towards disco) and then he does it again in the same album by having it end jarringly with the quiet "Dark Eyes" a simply structured track that features only Dylan, a guitar and a harmonica without any studio embellishment whatsoever.
JOJO did this in "The High Road" in this song Coming For You which is pop rock instead of loungy R&B of the album.
