Poás volcano is an active basaltic andesite stratovolcano with a major eruption about once every 50 years. At its peak is a lake, Laguna Caliente. Researcher Brian Hynek has sampled the lake and found only one microbe that lives in its ultradynamic waters.
Phreatomagmatic eruption at Poás volcano, Costa Rica
A phreatomagmatic eruption happens when water hits magma, resulting in an explosion. In this case, the eruption obliterated both the lake and the webcam that was monitoring it.
Poás volcano, minus its lake
Following an eruption, there is no longer a lake at the summit of Poás volcano.