When observations appear to violate the laws of thermodynamics (hot water freezes sooner than cold), there's something wrong with the data. The "proof" is other people making a similar mistake.
I don't profess to be an expert on thermodynamics but one of the folk who argued the subject admitted that it can happen at times. Times when convection currents in the hot water put more of it into contact with the ambient air more often, possibly leading to faster freezing. He also mentioned the point that hot water has less air in it and air has an insulating property in water.
Here is the article in case you decide to read it.
