Things actually can just "pop" into existence, the phenomenon that causes this are called quantum fluctuations. However, contrary to popular belief, they cannot explain the origin of the universe. The universe already needs to exist for a quantum fluctuation to occur. The truth is that the big bang tells the story of the moments after the singularity started to expand (by the way, the singularity is sometimes called the "primeval atom, but it's just a knickname, it wasn't an atom). We don't know the origin of the singularity, nor do we know why it expanded. Give it time though, 200 years ago we didn't even have electricity, it may take some time to crack the biggest mystery in science. I wish I had a better answer for you, but "we don't know" is the honest answer.
That being said, let me address your comment of "just a theory". Theory and law are about as good as it gets. Theories explain a phenomenon, make predictions, have stood up to testing, and are backed by factual evidence. Laws are proven observations that occur anytime certain conditions are met. The difference between them are WHAT and WHY.
A law states WHAT something is doing. Example: Kepler's Laws Of Planetary Motion state WHAT the planets are doing. Whereas a theory would explin WHY, the theory of gravity explains WHY the planets move the way they do. Theories and laws are not interchangable because they have very different definitions of what constitutes them, but once something is considered theory or law, it is accepted in the scientific community until it is falsified. Something cannot be "just a theory" because theory is the best rank to achieve. There is nothing higher, so saying it JUST a theory is an error.
Lastly (lots of questions in there, good for you), is consciousness. The human brain is a very very very complicated bio-computer. It even runs on electricty (seriously). The synapses between neurons in the brain operate in a similar way to a computer. It is completely feasible that one day we may be able to make computers so advanced, they are self aware and "conscious".