What happens when you shine a laser pointer at 650nm through a magnifying glass?

Several things happen.

Because the surface is curved, there is some reflection off the surface. Some of the incident light reflects. The light then starts traversing the medium along a path determined by angle of incidence, glass geometry, and material index of refraction.

Because its made out of matter two things happen while the light is inside the material. There is some small absorbtion, and there is some scattering.

When the internal light reaches the opposite surface some of it reflects internally, the rest of it is transmitted out at an angle determined by material index of refraction and glass geometry.

A high quality beam, with the right optics, can be focussed down to a spot that is about twice the wavelength of the light. If you have a concentrating lens (convex) then you tend to direct the light to a point. If you have great optics it works better, if you have a cheap lens, it doesnt.

If you have a dispersing lens (concave) then you tend to direct the light away in a cone. Its power decreases and is spread out.