Why does the Boiling Lake empty occasionally?
Research suggests that water levels at the lake are maintained by the bubbles of volcanic gases rising through spaces in the rock beneath the lake. When these gases are absent, the water in the lake is no longer being pushed up and the water level falls. The gases are sometimes absent because vents beneath the lake may become blocked.
Another possible cause for a drop in water level is that the rim around the lake may break allowing some of the water to drain out.