I've had that issue when I've made 2 mistakes:
1) Watering in such a way as to allow the leaves to become soaked
and
2) Doing so at non-dusk hours.
Correcting either 1 or 2 usually resolves the issue (for preventing future burn, at least). Your issue could be unrelated, but my experience says to try watering at sunset and/or prevent as much water as possible from soaking the leaves, and aim strictly for the base of the plant.