Exploding Stars
What most of the processes of star formation and solar system formation is known, there are many researchers who don’t know what happens when a star explodes. All we know is that when a star does explode, it is known as a supernova.
Dark Energy
Here’s what we know, dark energy seems to make up 73% of everything that exists, however, it still isn’t visible nor can it be measured. We just need the energy to balance out the mathematics of the Universe, but we may not ever detect this dark energy. Bit freaky.