Future continuous is a tense that says an action of the future that is interrupt with another especific action in present, future, or past.
Structure: Subject + will be + verb + ing + complements

Exemples: 

• She will be buying a phone, but when she goes to the shop they didn’t have the tipe that she wants.
• You will be running the race, but you broke your arm last week.
• They will be studying, but the teacher says that there isn’t any exam.