How to be sure of new tax residence?

Hi, I’m new here.
I am moving out forever.
So I am going to move to another country my residence.
But, in the new country I don’t plan to spend more than 90 days a year for sure, at least it’s not the plan for the first years.

But I want to be sure that my tax residence is in my new country, even if I spend less than 90 days a year.
I want to be sure I won’t be reclaimed by my original country or any other country that I might end up spending less than 180 days, but more than the less than 90 I expect to spend in my new country(looks like it’s going to be Portugal).

Hope that was understandable.

Does anyone know where I can get information about this kind related to nomadism?