Then pour over his head the torment of boiling water.
This is like the Ayah:
يُصَبُّ مِن فَوْقِ رُءُوسِهِمُ الْحَمِيمُ
يُصْهَرُ بِهِ مَا فِى بُطُونِهِمْ وَالْجُلُودُ
boiling water will be poured down over their heads. With it will melt what is within their bellies, as well as (their) skins. (22:19-20)
The angel will strike him with a hooked rod of iron and split his head open, then he will pour boiling water over his head. It will go down through his body, melting through his stomach and intestines, until it goes through his heels; may Allah protect us from that.
ذُقْ إِنَّكَ أَنتَ الْعَزِيزُ الْكَرِيمُ