I think maybe you got a chicken breast that was injected with water? Sometimes supermarkets do that to make the breasts plumper, the excuse being that it cooks up juicier. Also, did you start with a frozen piece of chicken?
Could there have been a coating of ice around it?

A tablespoon of lemon juice should not be enough liquid to poach it. Very odd...your kitchen adventures are more exciting and dangerous that the WOW campaigns!