There is a liquid sulphur geyser on Maviol planetoid. It is located in a insulated pool of water. For about 100 cycles it was functioning fine: there was hot sulphur coming out of the geyser and heating up the water around it. A couple of cycles ago (not sure exactly how many) I noticed, that the quantity of water has rapidly decreased, whilst its temperature remained very low. It turned out that there was hot sulphur coming out of the geyser, but it was not heating up the water around it, instead it was cooling it down and turning it into ice.