Hi! great site! I have been practising yoga for quite a few years now, including pranayama but sometimes while doing the latter, bhastrika specifically, my ears pop. Actually, only the left one does, usually. I would like to know if that's normal. It doesn't always happen so, but there are times when I feel it's not right.
Ears should not pop. Ensure that your breathing technique is correct and sitting posture is proper. Try to experiment with reducing the number of repetitions of bhastrika pranayama. Even after the issue is resolved, increase the number of repetitions very gradually.
Also, remember that bhastrika pranayama should not be done by people with low or high blood pressure or heart disease.