James,
Thats why you cannot make a cup of tea on Everest as the air pressure is so low , the water will boil before it gets warm.
Hot water will evapourate faster than cold water because the molecules have more energy , are moving faster and can therefore break out from the various bonds which are holding them.
This is scientific fact and as much as some manufacturers may like to contadict it , it remains fact
Being a sad git I found water chemistry really interesting , afterall with a low molecular weight it should be a gas.
cheers
Doug