Taking classes in an area of your interest is a great way to make friends, develop new skills, and improve your language skills. Music lessons, art classes, yoga, dance, Pilates, ski, cooking, and gym classes are the most popular in Sofia.
Some teachers offer these classes through their homes if it is a one-on-one class or they can come to you. There are even one-time workshops that can teach you a new skill.
You may connect with other expats in Bulgaria forums to find out about your options. Another option is to connect with your embassy's services as many put out a newsletter with listings of new classes. Hotels and hostels can also offer great information about local classes for adults. If you are looking for yoga, Pilates, or gym classes, then contact the local gyms and get a schedule of their current classes.