This is a discussion on 3Bet Call & All-IN within the online poker forums, in the Cash Games section; In late stages of Holdem tournament, I have seen low to mid stacks call 3 bet from early position and then go all in on
It could be a stop-and-go play. If the board comes out dry and relatively safe, they may jam on the flop which is definitely a +EV play.
But I've also seen players in low stakes adapt to this by jamming on the flop with a made hand. They're aware that some thinking players may assume that it's a stop and go and that you haven't made your hand. So therefore it would also be +EV to exploit thinking players this way, who are aware of the stop-and-go play.
It all comes down to the information you have on the player.
If it's a tricky player, then it's probably best to throw your hand away unless you caught something.