Kurt tank is right. The reason for the 'POP' could be that your panel is at max current draw. Add to that maybe some older motors that generate electrical noise. Another thing to think about when adding Dedicated lines is to 'balance' the load. What I mean by that is most homes have 2 phase power coming into the panel. Phase a and phase b. Now if the A/C - dehumidifier - refrigerator - toaster etc (follow me - high current devices especially electric motors) are on 1 phase along with your system there could be some very dramatic sags surges and spikes when those appliances turn on and off.
Did the 'popping' happen before the new circuits? If not you may want to have the breakers put on the other phase. Otherwise I might think about getting the motors and starting caps for the A/C and dehumidifier checked out.
Did the 'popping' happen before the new circuits? If not you may want to have the breakers put on the other phase. Otherwise I might think about getting the motors and starting caps for the A/C and dehumidifier checked out.