I've found a way to reproducibly crash the game.
Put all your units on auto-explore. Hit next turn. Eventually one or two of them will no longer auto-explore and you will be unable to click next turn - doing so does nothing. If you then move the no longer exploring units, the turn will advance.
Keep clicking next turn, the game will eventually crash - I've gotten it do do so on every game I've tried this. There is no error message (e.g. OOM / Dx call), just a standard windows error saying that the program has stopped working.