Wave-particle duality is something that we come across daily and are yet not able to visualize it. The thing is that even if we had the tools to visualize the wave particle duality we will not see it happen.
The mystery here is that when scientists try to observe this phenomenon, the photo/light waves are somehow able to know that somebody is watching them closely. Then it goes on to behave in manner which defies all previous readings.
We are still in the process of figuring out what happens to make it behave that way but the fact still remains that it 'completely defies physics'. Sooner or later we will find the reason behind it but till then lets enjoy this mystery.