It might melt
It might separate the disc's layers
It might explode
They're virtually indestructible by spinning
 
Correct Answer: It might explode

A little background…

Although it's unlikely to happen with most discs in most drives, there has been the occasional report of a disc exploding inside CD/DVD drives. In a majority of those cases, the disc was already damaged and spinning up was all it needed to shatter.

When tested by the TV show Mythbusters in 2003, it took upwards of 23,000 rotations per minute to make a conventional CD explode. That kind of speed is technically achievable with 48x and 52x drives, though the Mythbusters couldn't make a CD explode in a standard unaltered drive and resorted to other means.

Today there are many videos online of CDs exploding when being pushed to the limit, including footage of the disc coming apart at 170,000FPS courtesy of The Slow Mo Guys.