Yeah, as others have said, it's slow playing and sometimes also called trapping.
I've always liked to slow play, but more and more I remove this tendency from my game. You are letting opponents draw (to flushes and straights that will beat you) to cheaply, and you are risking them not building the pot enough for you to get the money in.
The latter is big deal, because if you wait till the river to bet, and the pot is ~8BB instead of , say, 15BB, you are very limited on what you can bet on the river before they realise you've hit a monster and fold. If you have built the pot prior to the river, you can make a sizeable bet and they'll still have
equity to call.
These days I slow play occasionally for balance and against opponents who are aggressive and like to barrel when the board is fairly dry (not too many obvious flush/straight draws).