Thermal decomposition of ester
Well, you are right. Esters decomposes at higher temperatures to form several small carboxylic acids and ketones and at even higher temperature, these carboxylic acids decomposes into carbon monoxide, carbon dioxide, carbon, oxygen and/or water. A paper[1] discusses about the thermal decomposition of ethyl formate, ethyl acetate and ethyl propanate at 1248-1638 K, pressure around 1.5 atm at a chamber filled with argon at a concentration of 2000 ppm. 

After the experiment, it was found out that 90% of oxygen has been released as oxygen gas and the pyrolysis mechanism was determined to be a six-centered decomposition producing equimolar ethylene and corresponding acid and at drastic conditions, it was known to have a dehydration reaction releasing water and a decarboxylation reaction to form carbon dioxide.

It was found out that EF gave formic acid, EA gave acetic acid and EP gave methyl ketene as the main products which subsequently decomposed into various smaller products at higher temperatures and the concentration ratios were noted.

Carboxylic acid can form white solid as noted in case of formic acid and acetic acid.

References


https://sutherland.che.utah.edu//USCI2013/PAPERS/1A07-070RK-0061.pdf