The general rule of thumb with popping or clicking in the jaw joint is that if there is no pain, it is probably nothing to be concerned with.  Other than scaring dinner guests and young children, the sound is basically just a symptom of a displaced joint.  If you are a chronic gum chewer, then this may be the cause.  If so, reduce the length of time you chew gum to less than 5 minutes at a time.

If the clicking is painful then you really need to see a dentist to determine if pathology is involved and discuss options for treatment.