This was motivated by:
Does an American citizen holding a Belgian passport need an ESTA to visit the US?
In most (maybe "most" is too optimistic?) countries, as a citizen, you have the inalienable right to stay in the country, no visa or other special thing needed. If anything, you would need to prove that you are indeed a citizen. You don't have to ask, being there your given right.
Usually, you cannot be "expelled" under any normal circumstances either, and at least in the EU (but presumably in many other countries?) it isn't possible to take away citizenship from you, even if you are the most undesirable, criminal vermin (though you can give up citizenship under some conditions).
You usually, under normal conditions, cannot be extradited as a citizen either. Although as Puigdemont's case showed, you can in principle very easily be extradited as a second-class-citizen, such as e.g. a regular EU citizen in another EU state who, as an EU citizen, has the same unrestricted, inalienable rights like everybody, but happens to be not-a-local-citizen of the country he is currently in (Puigdemont was lucky that Spain's claim of "rebellion" was deemed invalid by the court).
So the question is:
Are there are any countries where, as a citizen of that same country, having a valid ID or passport (or a siminar thing which proves that you are a citizen) is not enough to be admitted to enter (or stay in) your country?
@Matthieu M. brought up the idea that since there exist countries where you need an exit visa, it might be possible that you are expected to show such upon re-entry.