Pat Boone sings heavy metal?
William Shatner sings "Mr. Tambourine Man"?
These are extremes, and of course, created for the sheer hell of it.
But when Elton John took a left turn in Philadelphia in 1977 to work with Philly soul legend Thom Bell, I'm sure his idea was to create hits, not an E.P. than sunk faster than the Andrea Doria.
"Doing That Scrapyard Thing" was a Cream track written post-breakup, out of necessity. The band needed material to fill up the second side of a live farewell album. And while Cream covered a lot of unique ground for a power trio rooted in the blues, I think this song represents the best of their experiments. "Scrapyard" is a gem.
There are many obvious examples of artists venturing outside of their comfort zones, but rather than creating what will read as a laundry list---Dylan goes Christian, Bowie sings soul, etc.--can you restrain yourself to just one song, one wonderful, near-perfect selection that represents an artist successfully trying his hand at something new and different?