A word for an experience that must be lived

Solution 1:

A common phrase for such an experience is a "first-hand experience" or something that can "only be experienced first hand." A more informal way to say this is: "you had to be there."

Similar adjectives:

• personal/individual/unique experience
• a live experience
• empirical, hands-on
• indescribable, ineffable, beyond words

And so on. I was not able to find one that specifically refers to the need of such a first-hand experience in order to fully understand something. I typically hear phrases like, "You won't understand until it happens to you."

Solution 2:

Quale (plural: Qualia).

It's a mildly pretentious word, so use with caution. But I think it means what you want.