How is it possible to to Tevilas Yadayim in boiling water?
Thank you for your very valid question. I suppose one could say that fools will go where wise men fear to tread! After all, Amalek jumped into a hot bath, so maybe there are others who will do the same? That of course, is not as valid an answer as the question, because, as the Gemara says, we are not talking about fools. Seriously speaking though, Yad Soledes does not mean boiling hot. It means hot enough for a baby's stomach to get burnt, and (according to the explanation of the Meforshim) hot enough for the hand of a grown-up to withdraw upon contact. That will be pretty uncomfortable, I'm sure; but dangerous? I doubt it.
Incidently, bear in mind that boiling would have been described as 'Yad Nichvis Bo'. Remember too, that we are talking here about pouring the water over the hands, and pouring from a vessel automatically cools the water slightly. This we know from the Din of pouring from a K'li Rishon, which only cooks a K'dey K'lifah, instead of completely, which it could have done before the contents of the vessel were poured out. As regards Toveling or bathing in the Chamei Teverya, there again, nowhere are they described as 'boiling'. You might have found them unbearably hot, but somebody else might not. (I have seen people revelling in a Mikvah which I personally would have been unable even to place my foot into). And then, is it not perhaps possible that the temperature of the water differs slightly from place to place. Once again, many thanks for your question, Look forward to hearing from you again.
Be'virkas Kol Tuv