AA KK QQ were possible hands
Judging by your original post you did mentioned these as possible hands, BUT, according to the read that you actually went with you thought he had high cards and not a pair. When the turn hit you thought that he simply had over cards. ak aq or aj
you said his bet on the flop was a continuation bet as if you believed that he might have nothing but simply betting
If he was aggressive as you say he was, he's probably reraising your raise on the flop with aa kk qq (thats what I would assume).
For the most part you may have thought an over pair was possible PRE FLOP, BUT, the read you went with POST FLOP seemed to no longer consider aa kk qq as a possible hand, let alone any type of pair of that (because he could have had a pair under 9)
If you really thought aa kk qq were possible hands you were going against your original read of him having nothing heavily (POSTFLOP)BASED ON THE READ YOU WENT WITH POSTFLOP, there were no scare cards out there considdering how you read him in the hand.
Even if he had an overpair, that bet on the river still looks suspect and you still couldve bet 10-15 and got the same response out of him, betting lower amounts on the river will definitley save you money when you do get called by a better hand, because if he calls 27 most likely your beat, so if you can get him to fold with a 10-15 bet theres no need to bet that much.