Aha, know exactly what you mean. :-)
How much of the connecting part you have left? Not much you can do if there is nothing left, BUT if there is just a tinny little part still holding on use a lot if temperature resistant silicone smearing it all over the area and try to clamp the hose back on. Don't worry about the thing getting into your radiator, you will have to replace it anyway. In my case I was able to drive the car for a while with a slight leak. It didn't even empty the expansion tank until I got around to replacing the radiator, just a few drips now and then.