Burning
The finale was confused and lacking in important story points until I grasped Lee Chang-Dong's goal.
Others may believe that the film ended on a cliffhanger, but I believe that the way Lee Chang-Dong laid out the facts and mystery throughout this film made a slow burn film feel great.
The conclusion turns you into a detective, attempting to connect all of the clues to narrow down the cause of Haemi's disappearance after getting close with Ben. While everything eventually connects, it was still difficult to figure out the reason for Haemi's absences. Perhaps the hints offered did not reduce down to a single explanation, but rather created more alternatives. As other plots unfold, your solution becomes overshadowed, prompting you to seek out more clues in order to discover a new reason, and the cycle continues from the start to the end of this film.
While I'm not a huge fan of slow "burning" films, I have to say that definitely forced me to focus on tiny details and try to locate the engaging storyline myself.