Is there an issue with your boss right now in real life? If not, then your boss represents your ability to take charge and make decisions. Ask yourself where you need to be more authoritative in your life.
If dreaming of a former boss, ask yourself if there are any qualities that boss has that you could take on as your own right now to improve your current situation. May also be a reference to that time in your life, who you were when you worked for that person. Have you progressed since then?