What Causes The Knee To Pop?

Hi. I am 17 years old, and my knee pops alot. It never hurts or swells, but it is embarrassing. Would calcium help? I thought maybe if I drank milk it would help strengthen my knees, but I am not sure if this will help. I don't do alot of jogging or stretches, but I raise horses, so I am constantly moving, riding, and hauling buckets of water. Can you help me?