When the AA bottle is closed tightly, and the temperature fluctuates through time ammonia wants to evaporate.  The liquid ammonia becomes gas, and the bottle gets slightly pressurized, just like a soda bottle with CO2.  It can make a pop when opened. If the bottle was inverted or shaken before opening, or if dried silver is in the threads of the cap, it can cause that material to puff/spray out when opened, and cause a popping noise.   The good news is that it was stored properly, in a closed container.  There’s little that can be done to stop the popping, but make sure the cap and threads are dry and clean before closing, and store the bottle upright to minimize any of this action.