Visitor Visa and extending to permanent

What are the special circumstances for making your visitor visa into a permanent visa?  I read death and severe illness, but what else?

Virtually impossible except for the reasons you stated. Immigration are strict on this as people often come over on tourist visas then disappear into the woodwork to surface later on and try to claim a permanent visa.

Not sure where you have read that death or illness would turn a tourist visa into a permanent visa . If you are in Australia on a tourist visa without “ no further stay” condition, you can apply for all sort of temporary and permanent visas, provided you meet the requirements for the particular visa you are applying for.