It's not crashing, the process is still running, but will no longer respond to input from the player or the network, and is no longer drawing any graphics.

Switching the active console away from the X server (using ctrl-alt-f2 or similar) causes the game to become non-responsive, although sound continues. It appears to be an actual hang rather than just graphics freezing, as it will immediately disconnect other players in multiplayer as well with a ...

I have a save game with 3 consecutive tiers of the same infinite research queued. Attempting to remove any of them from the queue causes an immediate crash to desktop.