Personally I would only teach grammar on a "need to know" basis. You should be teaching communicative English in an interesting way and bring grammar explanations in only when necessary.
I think teaching English grammar using games would be good idea for your boring class. Students will feel fun when they learn English grammar, trust me they would be feel more excited. You can create new grammar games or just take from the existing books such as Longman, Cambridge, and so on.
You could also use pictures and other illustrative materials for better learning & also to caught their attentions while showing those things to them.
Goodluck! :-D