U tube closed vs. open, squeezing bottle

for a column of alcohol in a thin U tube (inner diameter 1/8 inch) partially filled with alcohol and extending from a sealed 3-liter bottle, represented by the figure below.

• When the top of the tube was open to the atmosphere a significant but modest squeeze of the bottle raised the level of the alcohol about half a meter.
• When the top of the tube was closed a hard squeeze barely changed the level of the alcohol.
• When the last half-meter of the tube was nearly level and open to the atmosphere the temperature change induced by the instructor's palm in contact with, but not squeezing, the container apparently caused the alcohol column to move a few centimeters within a minute or so.