If the players are expecting something to happen soon...

...

...

... Make them wait a bit. A minute or two of real time won't hurt in-game, and will increase the tension over whether what they're expecting to happen will actually happen immeasurably.

Transcript

GM: Nothing seems to happen. What do you do now?
Luke: Um...
Han: Are we still in combat rounds, or non-combat turns?
GM: Leeeet's just stay in combat rounds for the moment.
Leia: Did the torpedoes go in?
Luke: I think so.
Chewbacca: If this immediate vicinity is about to be subject to a major conflagration, it may be expedient to evacuate the area with alacrity.
Han: What?
C-3PO: Run away!!
GM: As you flee, your sensors detect a major power surge beginning in the Peace Moon...
Luke: What's happening?! I can't bear this!!!
R2-D2: Told you we should have tried to capture it.