What I've seen happening in the beta a few times is the Giant Blob Of Death:
If the remaining population is close to 0, the AI starts spamming an insane amount of cheap units (troopers, bazookas) and zerg-rushes you.
It can be countered by units/abilities with an AoE damage effect and is over once the AI has used up its remaining ressources (which might take a while...).
It can be tough to do so, however, esp. if you haven't encountered it before.

Last edited by El Zoido; 11/08/13 09:23 PM.