〜かと思うと ka to omou to
〜かと思うと（ka to omou to）means “no sooner ~ than, just when ~ then”. Follows the plain past form of a verb to say that no sooner had one thing happened than something else (often surprising or contrary to expectation) immediately followed. Formation: V-た + かと思うと（＝かと思ったら）
no sooner ~ than, just when ~ then
N2Formation
V-た + かと思うと（＝かと思ったら）
Explanation
Follows the plain past form of a verb to say that no sooner had one thing happened than something else (often surprising or contrary to expectation) immediately followed. The two events come right after each other, and the speaker is observing it with mild surprise. The second clause cannot be the speaker's own will/command.
Examples
Note
Interchangeable with 〜かと思ったら. The second event is something the speaker observes, not a request, intention, or invitation. Often conveys surprise at how fast it happened.
FAQ
〜かと思うと — what does it mean and how is it used?
no sooner ~ than, just when ~ then. Follows the plain past form of a verb to say that no sooner had one thing happened than something else (often surprising or contrary to expectation) immediately followed. The two events come right after each other, and the speaker is observing it with mild surprise. The second clause cannot be the speaker's own will/command.
〜かと思うと — how do you form it?
V-た + かと思うと（＝かと思ったら）
〜かと思うと — any usage notes?
Interchangeable with 〜かと思ったら. The second event is something the speaker observes, not a request, intention, or invitation. Often conveys surprise at how fast it happened.