Selamun aleykum. I am a doctor of medicine from Turkey. Today, I read a news, title of which was "what really happens when you die". According to this news, Cynthia McVey, a psychologist at Glasgow Caledonian University, investigated mortuary feeling, e.g. drowning, injection, decapitation, hanging, fire...
For fire she said, "Burns inflict intense pain, which helps to lessen pain sensitivity as superficial nerves are destroyed. Therefore some feeling is lost - but not much. Most people who die in fires are killed by inhaling toxic gases and asphyxiation."
http://thescotsman.scotsman.com/ViewArticle.aspx?articleid=3470701 - http://thescotsman.scotsman.com/ViewArticle.aspx?articleid=3 470701
QURAN, Women, 56 : "Those who reject our Signs, We shall soon cast into the Fire: As often as their skins are roasted through, We shall change them for fresh skins, that they may taste the penalty: for Allah is Exalted in Power, Wise."