Eggs "exploding" is well-known to bird breeders like myself. What happens is, an infertile egg or an egg where the embryo died in the shell will begin to grow bacteria that feeds on the dead yolk or dead embryo. The bacteria produce waste that forms gasses and sometimes the gasses produce enough pressure inside the egg to cause the shell to rupture.

It seems to be less common in reptile eggs because of the leathery, pliable shells that can withstand more pressure from within.