Sure, but you're going to be in a lot of trouble when you cross the international boundary - you may even get a armed escort.
You don't have to talk to anyone as long as you're not in controlled airspace that requires communication with ATC. It's not a good idea though. We pilots almost always announce our intentions at small airports and in certain airspace like sailplane and parachuting areas.
Entry into international airspace without pre-approaval nowadays is a BIG no, no...
thanks for the info ;)