There is a place in Hell and levels there called Boiling Excrement, where there is filth of souls —those who are cleansed of all the filth of this world. They are cleansed and ascend, and that filth remains there; and those evil rungs called Boiling Excrement are appointed over that filth; and the fire of Hell controls that remaining filth.

And there are those wicked  who soil themselves by their sins constantly and are never cleansed and die without teshuvah –those who have sinned and incited others to sin and have always been stiff-necked, never broken before their Lord in this world. These are punished there in that filth, in that boiling excrement, never leaving there. 

Zohar 2:150b (Daniel Matt translation)