Examine the hinges of the refrigerator door when you open it. Often, the popping noise comes from a damaged hinge with warped metal. If this is the case, consult your Frigidaire owner's manual for instructions on how to replace the hinge for your specific model.
Open the freezer door of your Frigidaire refrigerator. If you do not have the water supply line hooked up to your freezer, flip up the metal arm above the ice bin into the "Off" position. This turns off the ice maker and will prevent a loud popping noise that can sound like it's coming from the door.
Check the ice dispenser in your freezer door, if applicable. Ice falling into the door's dispenser can sound like a pop, especially if there is no ice in the dispenser at the time. While this sound cannot be prevented without turning off the ice maker, you will at least know this is a normal noise.
Check your owner's manual to see if your Frigidaire refrigerator has a self-defrosting feature. Frigidaire says that crackling, popping or sizzling heard once a day is a normal noise for refrigerators with this feature.