You may be experiencing a condition called snapping hip syndrome. In medical terms it's called external coxa saltans. The sound is caused by the iliotibial band (ITB) sliding over a part of the hipbone called the greater trochanter.
The ITB is a long piece of fascia (a thick layer of connective tissue) attached at the top to a hip muscle. It goes from the hip all the way down to the outside edge of the knee.
In between the ITB and the greater trochanter is a small, round cushion called the trochanteric bursa. As the ITB rubs over the greater trochanter, the bursa tries to cushion the friction. But repeated snapping back and forth can cause inflammation of the bursa called bursitis. When bursitis occurs the patient has both snapping and pain.
The first step may be to ask your dance instructor to watch how you are doing the barre or floor exercises that cause snapping. There may be an acceptable way to change your form. Stretching the ITB may also help. You can find a good series of stretches on-line at: http://www.nismat.org/ptcor/itb_stretch/. Doing something now before a painful response begins is always a good idea!