Explain the difference in the amount of expansion between gases and liquids.?

Well, when I piss my pants, my pants and maybe the chair get wet, but when I fart, the whole room reeks.

liquids are only liquids because they are attached to near neighbors (other atoms or molecules in the immediate vicinity). Gases have no such connection except very short-lived ones and over a few molecules or so at most. Thus, gases have unlimited expansion ability. Liquids cannot remain liquid except within a fairly narrow window of average separation distances. Basically, a liquid will convert to gas at some limit (and solid on the other end, of course). For this same basic reason, liquids tend to have modest changes in unit volume per change in temperature (or pressure) because there is a lot of energy involved in those attachments to near neighbors. Gases have no such energy to overcome so expansion and contraction is high for change in conditions. Solids, of course, have relatively tiny volume changes when conditions change. A lot of energy invested in keeping the atoms where they are so it takes a lot of energy to force them apart or closer together.

In a liquid, cohesive forces bond the molecules to one another. In water (the usual example!), each hydrogen is (loosely) attracted to the oxygen "end" of a neighboring water molecule. The polar covalent bonds WITHIN each water molecule are stronger than the intermolecular bonds just described, so the water does not assume a solid structure; but the cohesive forces permit molecular vibrations of only a limited magnitude. In a gas, each molecule is effectively separate, and each molecule flies off in whatever direction it happened to be traveling, with only rare, glancing collisions with other molecules. The difference is that the gas is hotter and hence the molecular speeds are high...the molecules don't "sit still" long enough to develop the intermolecular bonds described above, and even if they momentarily did, the high energy of the hot molecules would quickly break these bonds (which is just what happens when a liquid is boiled).