i dont think air even needs to be there.
if your water is at boiling temp, and your output has less resistance than your input, your pump will be PULLING on the boil kettle,not PUSHING wort to your fermenter/recirc-loop/chiller/etc.
at that temp, the water will boil under that slight 'vacuum', just like anywhere else: lab, mountaintop, coopers, muntons, etc.
air, entering the stream, does the same thing. so, yes check all your connections for airleaks.
but i agree, lower the heat a little. it will be safer for your pump and hoses too.