Villain is virtually unknown, 20/13 over 15 hands.

Not sure if this is worth mentioning. Villain had just been in a pot with a whale, he raised/4bet/called a 5bet shove, his button vs fish BB w/ QQ against 55 and ended up splitting the pot. This hand is IMMEDIATELY after that one.

PokerStars - $0.10 NL (6 max) - Holdem - 6 players
Hand converted by PokerTracker 4

BTN: $10.00
SB: $19.36
BB: $12.61
Hero (UTG): $10.15
MP: $15.32
CO: $11.11

SB posts SB $0.05, BB posts BB $0.10

Pre Flop: (pot: $0.15) Hero has Q Q

Hero raises to $0.35, fold, CO raises to $0.90, fold, fold, fold, Hero calls $0.55

Flop: ($1.95, 2 players) K 9 8
Hero checks, CO bets $1.50, Hero calls $1.50

Turn: ($4.95, 2 players) 3
Hero checks, CO checks

River: ($4.95, 2 players) K
Hero checks, CO bets $8.71 and is all-in, Hero ???

I don't understand what villain could have here? I don't see villain having a K, being an unknown we will assume the only Kx he 3bets is AK. If he does, why would he check a blank turn and then shove the river w/ trips?

Same reasoning if he had a set. I just don't see him checking the turn and then jamming river when he fills up...but what else could he have?

The only hand I can think of is missed straight draws but it seems unlikely he 3bets JT/76 pre.

Thoughts?