The asphalt has melted on the roads in Cumbria! It's wonderful that the weather is so hot. They have sent the salt gritters out to spread road stone on the bitumen. Bitumen has a high melting point because it is made of long, heavy molecules. I think that this means that there can be more intermolecular forces to hold the molecules together in a solid formation. More joins to separate means more themral energy needed so higher temperature. The explanations usually focus on higher boiling points. I haven't seen one that explains melting points.