I know that $p$-groups have the property, and all nilpotent groups also do. I wanted to have some non-nilpotent examples. Then I checked quasisimple groups, and found every proper normal subgroups of a quasisimple is contained in the center.
Quasisimple group ${\rm SL}(2,q)$ would be an example I want, when $q>3$ is an odd. For an odd $q>3$, the center of ${\rm SL}(2,q)$ is of order 2 and that makes ${\rm SL}(2,q)$ a non-simple quasisimple group with the property held; otherwise, for an even $q>3$, ${\rm SL}(2,q)$ has trivial center. Although ${\rm SL}(2,3)$ is not quasisimple, ${\rm SL}(2,3)$ also holds the property and is hopefully the example of the smallest order. My question is: How to prove ${\rm SL}(2,3)$ is the example of the smallest order? What are other kinds of groups that may be examples?
Thank you, any help will be appreciated!
Here's a quick way to check that $\mathrm{SL}_2(3)$ has the desired property using the computer algebra system GAP: