Most likely - a faulty CD. CDs can become cracked/chipped, or unbalanced (due perhaps to a sticker applied to the top, or a label applied not centered). Used to not be a problem with older (slower) CD drives - but as they've sped up (past 50x!!) more minor defects are having more serious side effects.
I saw a test once done by a European University (I think University, maybe a research centre) that tested CDs at high speeds - concluding I think that 48x was the maximum speed before A GOOD DISC could explode. Imagine what speed you have to spin a cracked disc at before it becomes a missile....
Course it might not have been the CD. It might have been the drive, or possibly something IN the drive that made it go bume.
Careful with that drive - I've seen drives where CDs shattered - the pieces can be blown INTO the drive, meaning the next disc to be inserted could potentially become a spinning disc of death too.