Used when the speaker wants to refer to a change compared to the past that they have directly seen or experienced. The speaker themself cannot be the subject.
Example
아침에는하늘에구름한점없는게하루종일맑을것같더니, 금방비가쏟아지네.
In the morning, there wasn't a single cloud in the sky, so it looked like it would be clear all day, but not long after it started to pour.
어릴때편식을하더니이제나도못먹는것까지잘먹는구나.
You were so picky when you were little, but now you even eat things that I don't eat.
2.
And then
and
Used to narrate a sequence of events directly observed by the speaker. The subjects of both clauses are usually but not always the same, and the speaker cannot be the subject. There is often a nuance that the first clause becomes the cause of the second clause.
Example
미나는부엌에가더니 5분만에라면을만들어냈다.
Mina went to the kitchen and made ramen in just 5 minutes.
구름이끼더니눈이왔다.
It was cloudy and then it snowed.
이야기중이던맥스가우리의대화를가만히듣고서있는앨리스를흘긋쳐다보더니입을닫았다.
Max, who had been telling a story, glanced at Alice, who was listening quietly to our conversation, and then closed his mouth.
눈시울이점점붉어지더니제이콥이결국참지못하고펑펑울기시작했다.
Jacob's eyes grew red until he couldn't hold it in anymore and started to sob.
3.
Related to past event
Used to express the existence of an additional event or truth related to something in the past.
Example
요즘부동산에집보러다니더니좋은집을찾았어요?
You've been looking at houses lately. Did you find a good one?