You could use the (experimental) CSS property hyphens
:
h1 {
-webkit-hyphens: manual;
-moz-hyphens: manual;
-ms-hyphens: manual;
hyphens: manual;
}
and specify the line break by using special unicode characters:
U+2010 (HYPHEN)
The "hard" hyphen character indicates a visible line break opportunity. Even if the line is not actually broken at that point, the hyphen is still rendered.
U+00AD (SHY)
An invisible, "soft" hyphen. This character is not rendered visibly; instead, it suggests a place where the browser might choose to break the word if necessary. In HTML, you can use to insert a soft hyphen.
EDIT
As mentioned by @hustlerinc it might be needed to set word-break: break-all
to make it work.