"Most people" refers to a general population. For example: "Most people like ice cream". (most people anywhere) "Most of the people" is more specific to people in a certain area. For example: "Most of the people in this room liked the movie".

Great answer and clear examples given. Cheers

We say "most people" when talking about an assumed contextual population, e.g. Most people would agree that murder is bad. Most people have never been to Antarctica. I've never been to Antarctica, like most people. You can see that the population is assumed without any reference. On the other hand, we use "most of the people" when explicitly given a population (some grouping of people), e.g. Most of the people on the train are not wearing hats. I really like my class--most of the people are friendly.