What does "there comes a certain point..." mean?

[Hongrui]

I've seen this sentence before, but I can't catch the exact meaning. So, I post here for your help. If you could give some examples, that would be better. Thanks in advance.

I've seen it in this sentence, "There comes a certain point when you just know you’ve had enough of life."

Besides, does "I've had enough of something/somebody" mean I'm tired of something/somebody, I'm annoyed with it. Am I right?
Many thanks to you who can help me.

[Mister Micawber]

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There comes a certain point when you just know you’ve had enough of life-- This is not an idiom. Point= time, stage, position.

Besides, does "I've had enough of something/somebody" mean I'm tired of something/somebody, I'm annoyed with it. Am I right?-- You are right.
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Native English teacher at Mister Micawber's