Over at Daystrom, this comes up from time to time. I've formed a head-canon for it as well. To quote one of my comments on a thread there regarding the explosions (and the "rocks"):

My understanding is that the "rocks" are a product of the electroplasma system being exposed to air. Whether that is some sort of coolant that is meant to seal the EPS leak in that console or some sort of EPS byproduct reacting in air, I don't remember or have a head-canon for it.

All of that said, if I form this reply into one worthy of Daystrom, then I say it is an intended safety mechanism to protect the crew against catastrophic failure of the EPS conduits.

So, the consoles are exploding from the failure of the EPS conduits and the expansion of the coolant.