Is there an equivalent of heaven and hell in Buddhism?

According to most sources, a soul stays in *samsara* until it concentrates enough *karma* to get yet another rebirth. However, I failed to find any sources explaining if this process is eternal. In other words, what happens if a soul has committed so many sins that it's unable to accumulate enough *karma*? Or, in other words, is there a "dead end" when no more rebirth is possible?