there is a hissing sound coming from underneath the bonnet

hi have a problem with my car, temp gauge is fine no overheating, no smoke, no smell no indicator light on car. my car just stalled got heavy and stopped but waited a couple of seconds and was able to drive home. heard a loud hissing sound coming from a pipe or hose but could not find it. left it over night and found a puddle of water on the floor. what could this be? any info is appreciated.