A result, criterion or standard in the following action is expected and necessary for the first clause to be realized. Like -게, but with more emphasis.
Example
아무도눈치를채지못하게끔조심스럽게과자를훔쳐먹었다.
I ate the snacks stealthily such that no one would notice.
'떡밥' is a figurative expression for the phenomenon in which a plot twist or new information is hinted at before it is directly revealed, so that readers have the chance to guess.