Could you try to Bullrush someone if they're grappling you? Seems mechanically similar to punishing kick, and I can't think of any reason why you wouldn't be able to off-hand. Though it would still be a CMB check and only better if you have special bonuses to bullrush.
In any case, it's a tricky situation in general and can vary based on the situation. In most cases, I'd probably go with giving a free check to break the grapple, maybe with a bonus.
Teleport-style effects would be automatic, I think, assuming you can make them go off (concentration checks are hard in grapples). Isn't there a feat that lets you forcefully follow a teleporter while you grapple them?
Since "Grappled creatures cannot move", I'd say you can't use Bullrush, since bull rush is you moving a target. Reposition might work, though.