Most of and almost all of are pretty much identical in meaning. I can't really see much difference. Maybe almost all could mean more than most of, but I wouldn't be too sure about it.
Most of the students are finished with the exam. (7 or 8 out of 10?)
Almost all the students are finished with the exam. (8 or 9 out of 10?)
What do other native English speakers think about this?
1. Madona is the MOST popular singer in 90's
2. We ALMOST ALL will come to home at 5 p.m.
Google translater will help you)))