One explanation[1] i heard is observation is a actually equivalent to entanglement. Now we know that two elements entangled will have to maintain the state corresponding to its entangled peer. Now if you observing (or taking measurement) the whole system gets entangled to the particle. you are observing and hence the wave function collapses.

You can look at a better explanation here [1]https://www.youtube.com/watch?v=dEaecUuEqfc