Ice volcanoes aren't proper volcanoes. Instead, they are a phenomenon that can be found where there are holes in crusts of ice that float on water. The water erupts from the holes when the waves move underneath them, forcing some of the water to turn to ice shortly after hitting the air.
I found this ice volcano video on weathernationtv.com. If you're interested in learning more (and seeing more videos!), Science Alert has a great article on it.