Kamala, as any other people receiving powers from the activation of latent Kree DNA, gains them when exposed to the terrigen mists unleashed on the planet by Black Bolt. I believe this happens in some major title or crossover, like Infinity or Inhumanity.
All of these people come to be called "NuHumans", or "New Inhumans", because as opposed to Inhumans they are not Inhuman born but just have latent Kree genome in their DNA, deriving from the early Kree experimentations on the human race.
When exposed to the mists, either the special abilities manifest, or they apparently die in the process (this could not happen with Inhumans exposed to terrigenesis, I believe, as their inhuman DNA is always enough).
Kamala knows nothing about this until she meets Lockjaw that brings her to Medusa, so you have not missed anything.