How to handle a check-raise on the Flop

[Kico9]

2-5 No limit. I have $900. Villain has $500. Villain is loose aggressive and likes to see flops even with marginal hands. I raise from UTG with AQo to $20. It is folded around to Villain in the BB who calls. Flop comes 9 7 4 rainbow. Villain checks. I bet $25. Villain check-raises to $80. I think Villain would make this move with nothing at all or may have something like middle or bottom pair. Should I have checked after he checked? Should I now call and see what happens on the turn? Should I re-raise $100 more and see what he does?