verb
-solves; -solved; -solving
of something solid :to mix with a liquid and become part of the liquid [no obj]
[+ obj] formal :to officially end (something, such as a marriage, organization, or agreement)
somewhat formal :to end or disappear or cause (something) to end or disappear [no obj]
If you dissolve in/into tears/laughter, etc., you start to cry, laugh, etc., in an uncontrolled way.