I am unable to replicate the issue, but it happened twice while inside Freehold during LFG (once before and during the first boss). As soon as a puddle was placed on the ground, where I was standing, my game instantly seized and crashed to the desktop. I was given a crash report, but quickly closed out of it in an attempt to rejoin my group. Further attempts to replicate the issue have failed, including heading inside on my own and causing a ground effect to occur by the flying boss above both while in and out of combat. Nothing so far.
This has happened once before while LFGing inside a TBC instance; I want to say Shadow Labs.
Fresh install, can give system info if needed. A quick Google search did not show any similar results, though I went about it quite lazily and very well could have missed something.