The phrase "big cliffhanger" means a suspenseful ending to a book, movie, or TV show that leaves the audience wanting to know what happens next. Full definition
The Berserk anime's ending is a serious contender for biggest cliffhanger ending ever, and Berserk fans will be pleased to know that Berserk and the Band of the Hawk goes further into the Berserk story than either of the anime series». (cogconnected.com)
It is in the nature of big cliffhangers to be trapped in a state of irresolution, to be re-judged after their resolutions arrive. (vox.com)
I know the first film was left with a pretty big cliffhanger but it was a good cliffhanger. (mediamikes.com)