A face will burn before it melts.
Different materials react differently to different temperatures. Every material will melt at a high enough temperate. But some materials will undergo autoignition before they melt. A material that auto-ignites must be able to sustain a oxidation chain reaction in air in order to stay on fire. That is, once the material auto-ignites, the oxidation reaction of the material with oxygen in air must be exothermic, so that the reaction causes a follow-on auto-ignition in nearby molecules.
Materials like metals without highly exothermic oxidation reactions will melt into a liquid before the 'burn' in oxygen. But organic materials, generally, will ignite and carry out exothermic reactions. Carbon reacts with oxygen to make carbon dioxide, hydrogen to make water, and nitrogen to make various nitrogen oxides. All these 'burning' reactions will happen at a lower temperature than the melting point of the organic materials that make up the human body, like collagen or keratin or live cells.
For a living creature, the water must be driven off before temperatures will rise enough to auto-ignite, but the fact that creatures are ~75% water means their temperature will stay in the range of 100 C (the boiling point of water) until all the water is driven off. Once the water is driven off, the organics will auto-ignite with increased thermal energy, before they melt.