Top radiator hose blew off, I put back on filled back up with antifreeze. why?

Possible motor mount problem!!!... Engine shifting when selecting/shifting into gear.....actually pulling on hose!... Now i certainly didn't make this up... I've seen it happen!!!!!.. With a helper to watch... shift into reverse, while holding brakes, rev engine a bit... Have helper see if engine moves excessively... Now try it in DRIVE.. see if it moves excessively in other direction.