I tried to take help from my dictionaries, but they didn't offer much. Emotion: zip it

Pop in

Pop over and

Pop out

All these words seem to mean "go" or "come" but the usage is not easy. Could you please help me? Do you find these sentences natural?

I'm popping out to the shop. will be back soon.

I might pop over to your place at about eight. Just expect me.

If you're free tonight, can I pop in for some time?



PS: eight or 8. Same?
The way you have justed 'pop' is correct. Eight or 8 doesn't matter is this informal usage. For formal use write the word but this is an informal dialogue and most likely to be said or maybe texted.

I wouldn't use might and the just together. I might pop over............, so expect to see me. I will pop over......,expect me.
Perfect! - with regard to the situations in which you would use each.

1. Either, "I'll be back soon" or "Back soon." or even, 'Be back soon", but not, 'Will be back soon."
2. Why add, "Just expect me?" Maybe you have a reason. It just seems unnecessary, since 'popping over' indicates 'so expect me'.
3. Omit 'for some time' . The whole idea about popping in, out, or over, is that it's a quick, short event. If not, then say, "If you're free tonight, could I call in to discuss..."

You are not referring to 'how many books = eight, but time, and we write time in numbers '...about 8.'
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 Dave Phillips's reply was promoted to an answer.
You can't say "MIGHT pop over' and then say, 'so expect me'.
If I say, "I'm going to be down in London on Saturday, so I expect me", the recipient of the message would stay in with the full expectation that the person would be calling.
'might' expresses only "possibility". Hence, I wrote:

Don't say 'just expect me' or even, 'expect me'. It isn't logical.
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Might pop over