I am a student finishing my Masters in physics and I will be taking a gap year before I start a PhD. I plan to use some of this time to self study some of the courses I have already taken, in order to deepen my understanding and to form better intuition. I would like some advice and resources on how to "actually understand" quantum physics.

To make this question more specific I think I should explain what I mean by this. What do I consider "actual understanding"?

A quick answer to this question is that I am taking an instrumentalist approach to quantum theory and ideally I would like to study detailed descriptions of quantum experiments so that I can better understand exactly how the mathematical models that I have been taught in class correspond to the results of these experiments. I am stressing the word "results" here because I am not really interested in what is happening in between the measurements since it is still an open question (the interpretations of the quantum formalism). Essentially, I want to equip myself with all the experimentally verifiable facts before I can dive into deeper topics.

To make the above more concrete: