Ask HN: Concurrent Programming Projects for beginners?

I have spent a lot of time writing web applications from backend-to-front end (I am sure there is lot more to learn there), but I got bored and wanted to learn something I never learned(and wanted to).

I am talking about Concurrent Programming. I mostly work with Java but in order to learn Concurrency, I picked Erlang and I want to invest my time learning this language and do some projects to further strengthen my understanding.

I admit, that I love Erlang for the parts I read so far. I like syntax(its not verbose) and a very different approach to programming.

I want to ask what projects a beginner can work on related to Concurrent Programming Model. I am blank headed right now and need guidance.

Please enlighten me with your advices and experience. Books, resources, videos, etc all are very much welcomed here.

Thanks a lot in advance