Re: Why is the milk in a pan climbing abruptly when we heat it ?

I am not entirely sure I understand your question but I will try to give 
you a few ideas anyway.  If you could clarify the term "climbing" a bit 
better - describe this behavior in more detail - I will try to send you 
another posting if I can help further.

For the moment, there is one thing that immediately comes to mind when you 
said "climbing". Gases become less soluble in liquids as the temperature 
increases.  It is possible that the gases dissolved in the milk aren't able 
to escape fast enough from the liquid, resulting in sudden and unexpected 
movement in the surface of the liquid as bubbles erupt.  You can try a few 
things: stir the milk as you are heating it, apply the heat more slowly, or 
add a small, non-reactive, rough object (like a boiling chip) to the liquid 
so the dissolved gases have a surface on which to form bubbles.

Another part of the problem I think you are seeing is the result of 
proteins.  Milk proteins are very good at coating bubbles and stabilizing 
foams.  Because the dissolved gases are trying to escape in the form of 
bubbles and the milk proteins are making the bubbles last longer than they 
normally would in just water, the volume of the liquid is going to rise as 
you heat it.  The gases are expanding as they are heated inside the 
bubbles and, since the milk proteins don't let the bubbles pop easily, the 
bubbles are getting larger.  Again, stirring or applying the heat more 
slowly may help you avoid the "climbing" you are seeing.

Anyway, I hope this information helps a little and good luck with your 
milk!

Kieran