I am currently attempting to make kheer, which involves simmering milk for a long time to reduce heavily, and then adding sugar near the end for the last 2-3 minutes. I've also noticed this is a trend with other recipes which involve boiling/reducing a liquid for a long period of time, they usually specify adding in the sugar near the end rather than the beginning. (Saw similar instructions in chai recipes as well)

Does anyone know why this is? What is the difference between adding sugar at the beginning of the reduction process versus adding it near the end? I looked online, and then only thing I could find is that sugar raises the boiling point of water, but I'm not sure I buy that explanation. It sounds like the purported reason that people add salt to water to lower the boiling point (which it does, but not noticeably). Anyone have some insights behind this?