The easiest way to tell if a scene is over is to think whether you could skip ahead a little without messing things up. If the action is continuing, it's the same scene. If narration is continuous in a way that isn't, "And then, later that day..." type of way, it's probably over.
When in doubt, I ask the players. "Hey, guys. I think this scene's done. Anyone against me skipping ahead a bit?" If no one has objections, the scene is done.
I'm very much against ending scenes with someone crashing through the window to pick a fight. That's a great way to START a scene, don't get me wrong. But if something worth paying attention to is going on in the room, someone smashing through the windows is definitely the middle, not the end.