Simply hitting "End Turn" essentially caused a crash.
* I can't recreate it, the autosave does not reproduce this crash.
I mentioned in another post that I stumbled on a workaround. When end-of-turn crashes were happening to me, I started saving more often so I wouldn't lose as much progress. I've found that when I manually save (not autosave) every turn, I never get an end of turn crash. My guess is it's related to the autosaves.