I have an older home. It's 4 layers of brick thick with the floor joists tied into the brick. At some point an addition was constructed with the same brick construction. The rear was stuccoed at some point, likely to cover up some damage. I am in the process of removing the stucco but I ran into an unexpected problem.

There seems to a large patch that looks like it was poured. Although it looks kinda like cinder block and is very easy to break. Both ends of the wall are still brick. I don't want to pass the point of no return and have to rebuild the entire wall. Right now I can still patch and reapply a new top coat of stucco if I had too. Any thoughts or suggestions would be appreciated.

I also apologize if this appears twice I tried to post this earlier and it never appeared. Thanks in advance, Joe.